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161.
The α-alkyl β-oxoesters undergo type II photoreactions. The process of back hydrogen transfer in the 1,4-biradical intermediate to revert to the starting ester is suppressed because of the intramolecular hydrogen bonding between the hydroxyl and carboalkoxyl groups in the biradical intermediate. The hydrogen bonding determines the stereochemistry of 1,4-biradical cyclization. The cyclobutanols having the hydroxyl group cis to the carboalkoxyl group are formed exclusively from the α-alkyl β-oxoesters . The enol form of the type II elimination product, the benzoylacetate , acts as an effective internal filter for the photoreaction of the α-alkyl β-oxoester . 相似文献
162.
Kenji Moriyama Tomohisa Nagamatsu Fumio Yoneda 《Journal of heterocyclic chemistry》1986,23(1):241-243
A new-type pyridodipyrimide, 8-methylpyrido[2,3-d:6,5-d']dipyrimidine-2,4,6(3H,10H,7H)-triones were prepared by the condensation of 6-alkyl- or 6-aryl-amino-2-methylpyrimidin-4(3H)-ones with 2,4,6-trichloropyrimidine-5-carbaldehyde or 3-alkyl-6-chloro-5-formyluracils. The pyridodipyrimidines thus obtained oxidized alcohols under neutral conditions to yield the corresponding carbonyl compounds and a significant autorecycling in the oxidation was observed. 相似文献
163.
We here demonstrate the creation of novel poly(aniline) (PANI) nanofiber structures by a polymer wrapping method using schizophyllan (SPG). Mannose-modified SPG can also wrap PANIs to give nanofibers having a lectin affinity. This interaction is applicable to designing novel PANI/protein composites. The results establish that SPG can act as a novel "host" to assemble PANIs into one-dimensional superstructures. [reaction: see text] 相似文献
164.
The oxidative coupling of 2-naphthol and 3-hydroxy-2-naphthoate derivatives with a copper catalyst under an O2 atmosphere was carried out. The reaction in the presence of a catalytic amount of the Lewis acid, Yb(OTf)3, proceeded in a cross-coupling specific manner. 相似文献
165.
Kazuyuki MiyashitaHidenobu Murafuji Hiroshi IwakiEito Yoshioka Takeshi Imanishi 《Tetrahedron》2003,59(26):4867-4872
Catalytic transformation of serine-O-carbonate to S-aryl cysteine derivatives was successfully achieved in the presence of Li+ by the use of a pyridoxal model compound having an ionophore function, which is the first example mimicking cystathionine β-synthase, artificially. 相似文献
166.
On DDQ oxidation under anhydrous conditions, hydroxy groups located at α or β position to methoxybenzyl ether groups were readily protected by the intramolecular oxidative formation of acid-sensitive methoxybenzylidene acetals, which were further oxidized to alkali-sensitive hydroxy esters in the presence of H2O. 相似文献
167.
35Cl and 19F relaxation time measurements were carried out on symC6Cl3F3. The analyses of the 19F high-resolution NMR spectra and the 35Cl spin-lattice relaxation time showed that the crystal belongs to a trigonal or a hexagonal crystal system in which the molecules undergo three-fold reorientation about the molecular figure axis with the correlation time τc/s=3.42·10?7 exp(18.2 kJ mol?1/RT). Temperature dependences of the 35Cl NQR frequency and 19F spin-lattice relaxation times are such that only a minor structural change is associated with the phase transition at 296 K. 相似文献
168.
169.
S Yoshioka Y Banno Y Okano K Ohki Y Mizukami 《Chemical & pharmaceutical bulletin》1992,40(4):1016-1021
We investigated the distribution and fate of liposomes after their intravenous injection into a mouse. Liposomes were composed of dimyristoylphosphatidylcholine, cholesterol and dicetylphosphate (7:2:1, molar ratio) with or without lactosylceramide. They were characterized as small unilamellar vesicles, approximately 100 nm in diameter, using gel-exclusion chromatography on a Sephacryl S-1000, freeze-fracture electron microscope and dynamic light scattering method. Liposomes were very stable in serum as seen by the results of leakage of the entrapped marker and electrophoresis experiments. We demonstrated that liposomes were internalized by way of an endocytotic process via coated vesicles detected in the electron microscope. The increase in liver uptake of lactosylceramide-bearing liposomes was mostly accounted for by enhanced uptake in the parenchymal cells, while uptake by non-parenchymal cells was only slightly increased. This observation supported the notion that a galactose-specific receptor was involved in liver uptake of lactosylceramide liposomes. The lactosylceramide-bearing liposomes were preferentially recovered in the liver and were found to first be predominantly localized in the mitochondria-lysosomal fraction. They were then decomposed by lysosomal enzymes, and the hydrolyzed components were reincorporated into membrane phospholipids in the microsomal fraction. At the same time, a rapid and reversible exchange of phosphatidylcholine between microsomes and mitochondria was demonstrated. 相似文献
170.
Ohtera Yasuo Sato Airi Kawashima Takayuki Takaya Tomohisa Okura Yuki 《Optical Review》2022,29(2):140-152
Optical Review - Multi-spectral filter array composed of a wavy alternating dielectric multilayer was integrated on a CMOS image sensor of the Raspberry Pi HQ Camera. The filter array consists of... 相似文献